Garnet have released their quarterly smartphone sales numbers, which they claim are sales to end users.

We do not normally have a bone to pick with their numbers, but their latest numbers seem to me to be somewhat out of kilter with reality, and if true would mean a massive collapse in Windows Phone 7 sales worldwide.

According to Gartner only 1.723 million phones running Windows Mobile + Windows Phone 7 were sold to end users in the second quarter of 2011, down fro 3.658 million in Q1 2011.

This would represent a more than 50% drop in combined sales over the last 3 months, a number which seems somewhat unlikely. Last quarter they also released specific Windows Phone 7 numbers, pegging this at 1.6 million, a number which is nearly as big as the total number for Q2 2011, suggesting Windows Mobile sales have been nearly wiped out.

While Windows Mobile sales may have dropped, and Windows Phone 7 handsets now outsell Windows Mobile, in most areas the numbers are still close to 50:50, as can be seen in this Kantar data.

Moreover, looking at WP7 Facebook usage numbers it seems new WP7 devices were being activated at an extremely steady rate between Q1 and Q2 2011.

In fact 206,213 users were added in Q1 and 196,014 users in Q2, a slight drop, but nowhere close to 50%.

So while it is certainly possible 1.7 million Windows Phone 7 handsets were sold in Q2 2011, I suspect as a combined WM and WP7 number (which was confirmed to me by Gartner) the estimate appears pretty wrong.